| Primary satellite | Secondary satellite |
| Name | Cosmos 1821 Rocket | DMSP 5D-2 F13 DEB |
| Spacetrack catalog number | 17526 | 40565 |
| Radar cross section | large | small |
| Epoch of two-line elements (UTC) | 2021 Apr 12 10:56 | 2021 Apr 12 09:44 |
| Time of closest approach (UTC) | 2021 Mar 03 18:45:23.966 |
| Minimum distance | 7.531 km |
| Height difference | -5.683 km |
| Relative speed | 14.703 km/s |
| Angle between velocity vectors | 178° |
| Geographic position | 11.1°N, 25.4°E |
| Height | 991 km |
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